2 Answers
2

This looks like the effect of noise reduction at high ISOs. Heavy NR is common in compact cameras with small sensors. Fujifilm does it better than most, but there's only so much blood you can get from a stone.

On most modern high-megapixel point and shoot cameras, you'll see this even at low-ISOs if you pixel peep. It's important to note that in most cases, this is actually okay, because for printing or at common display sizes it'll look just fine. Better quality gives you more room to crop, of course. And in this case the sky looks particularly bad, so with this camera I'd try to stick to lower ISOs.

More advanced models often have the option to turn off noise reduction, and I usually do, because I prefer the look of noise to this "painted" blur. Or, if you shoot RAW, you have many, many options for more flexible noise reduction in post.

Thanks! With that information I found ephotozine.com/article/… which shows the different ISO settings. I'll try it out for sure later.
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WexJul 31 '12 at 4:01

2

Excellent answer. Would like to add that if you have Lightroom, you can simulate this by using the noise reduction slider. Set it to a very high value, and you see this exact same artifact appearing.
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FerdyJul 31 '12 at 19:22

I'm wondering if a low image quality/high compression ratio could also be contributing to problem.
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James GrayAug 2 '12 at 3:58

The effect can be explained by heavy noise reduction caused by using too high a shutter speed for the circumstances.

The specific camera is worse than most in its class in this respect.

The 1/2000s exposure time is unnecessarily fast and as a consequence the ISO "film speed" is high, making the image more noisy than it needs to be.

At a guess that would be about a classic f/8, 1/125th ISO 100 photo.
If the camera used f/4 (a guess) then at 1/2000th

ISO needed would be 100 x (f/4/f/8)^2 x 2000/125 =~~~~ 400.

This may not be correct, but as seen below, 400 ISO would not be king to this camera. A MUCH slower shutter speed will allow a low ISO setting to be used and will improve the image quality - although the DPReview comments make it clear that it's worse than most in this respect.

In good light and at base ISO all cameras in this group test will do the job. The difference between the best and worst in class is relatively small and only visible at large magnifications (close to 100%). The contestants can roughly be split into three groups. At the very bottom only the Fujifilm S2500HD is, with its excessive application of noise reduction and consequent smearing of fine detail really visibly worse than the rest.

I think it is funny that they even included ISO 6400. It is terrible on this camera.
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dpollittJul 31 '12 at 14:42

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+1 for the extra info. It does appear to be the camera's fault as opposed to anything else. It was bought as a cheap 'first entry' into photography, and it looks like it's done it's job by teaching me something at least :)
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WexAug 1 '12 at 3:38

@Wex: It's not only the camera's fault. According to the EXIF data, you used shutter speed priority and selected 1/2000 s shutter speed. This was a bad choice of yours that forced the camera to select a very high ISO. Any small-sensor camera with this settings will give you bad image quality, although your camera is worse than most in this respect.
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Edgar BonetAug 2 '12 at 9:45